Powder slurry compositions have been used to provide a variety of advantages in the coating of articles. Powder slurry compositions typically include a first component that is in a solid particulate form and a second component that is liquid. The first component is dispersed in the second component to provide a slurry which can be applied using conventional spray application equipment and techniques.
Aqueous powder slurry compositions provide the advantages of powder coating compositions with the ease of application of traditional solvent borne coatings. As a result, powder slurry compositions have the potential for environmental and financial advantages.
However, powder slurry compositions do present performance and application challenges. Traditional powder slurry compositions typically utilize epoxy acid resin systems. Such systems often sacrifice scratch and mar resistance in order to obtain acceptable water resistance, chip resistance and etch resistance. The nature of the powder coating composition used in the powder slurry composition requires that temperatures above the T.sub.g of the powder resin be used followed by temperatures sufficient to affect crosslinking. Thus, high cure schedules are often required.
Application concerns typically require the use of powder slurry compositions having lower Tg resins. The use of lower Tg resins facilitates more rapid flow and improved appearance. However, storage and manufacturing problems can result when powder slurry compositions having lower T.sub.g resins are utilized. Manufacturing is particularly challenging, especially with acid epoxy resin systems. Separation, precipitation and/or agglomeration of the solid particulate component during storage may also be observed.
Inferior film adhesion and/or cracking of the applied powder slurry film during curing are sometimes observed. These negative performance characteristics can be magnified by higher film builds and storage stability.
Finally, finished films obtained from powder slurry compositions can exhibit lower gloss and/or inferior performance characteristics, particularly when balancing scratch and mar resistance against water resistance, chip resistance and etch resistance. It is often difficult to achieve an acceptable balance of properties among these characteristics, especially with traditional acid epoxy powder/powder slurry resin systems.
Thus, it is desirable to provide improved powder slurry compositions wherein the foregoing disadvantages are either eliminated or are minimized. Prior art attempts hereto have been unsuccessful.